AUHostTransportStateBlock

If the host app provides this block to an audio unit, via the transportStateBlock property, then the block may be called at the beginning of each render cycle to obtain information about the current transport state. Any of the provided parameters may be null to indicate that the audio unit is not interested in that particular piece of information.

This block returns true if the transport state was able to be retrieved from the host; it returns false otherwise.

The block takes the following parameters:

transportStateFlags

The current state of the audio transport.

currentSamplePosition

The current position in the host’s timeline, in samples at the audio unit’s output sample rate.

cycleStartBeatPosition

If cycling, the starting beat position of the cycle.

cycleEndBeatPosition

If cycling, the ending beat position of the cycle.